Train-control system for railroads



Nov.

C. S. BUSHNELL TRAIN CONTROL SYSTEM FOR RAILROADS Original Filed Jan. 26. 1922 3 Shanta-Sheet 1 Nov. 2 1926. 5

C. S. BUSHNELL TRAIN CONTRGL SYSTEM FOR RAILROADS t 22s 21s- 59 *T 235 2&1 249 234 236 azs 224 L 237 ass F 16 n 3 5 P 259 T 1 A I ii 225 1 L iii P R 1 202 is n (C I k k wi h a T 12 20 r L NTOR Nov. 2, 1926. 1,605,525

C, S. BUSHNELL TRAIN CONTROL SYSTEM FOR RAILROADS Original Filed Jan. 26. 1922 I5 Sheets-Sheet 5 l I l l FIGS,

Patented Nov. 2, 1926.

"UNITED STATES, PATENT oFFicE.

cmnnns s. BUSHNELL, or Rocnnsrnn, NEW YORK, 'ASSIGNOR TO GENERAL BAIL- WAY SIGNAL COMPANY, or earnsiNnwyonx, A CORPORATION on NEW YORK.

TRAIN-CONTROL SYSTEM FOR BAILBOADS Original application filed January 586, 1922, Serial Io. 531,903. Divided and 18, 1928. Serial No. 639,482.

This invention relates to automatic train control systems for railroads.

In train control systems, it is necessary 'to transmit or communicate controlling in fiuences or impulses from the trackway to v moving vehicles, in order that the train'control' apparatuson each vehicle may be 'governed in accordance with the presence or absenceof other vehicles, positions of switches, and other conditions affecting the safe prog- 'ress of the vehicle. Gn account of weather conditions, problems of .clearancepand like difiiculties encountered in practice, it is de, sirable to communicate such contro ling in-' fluences inductively, that is through an'intervening air gap, rather than by a mechanical cooperation or physical contact between devices on the vehicle and devices on the track. With a view ofsatisfyin the principle of failure on the side of sa ety, so important in, railway signaling. and train control sys- 't'ems, it isconsidered preferable to employ an arrangement of car apparatus and track- 'way devices which will act to produce a stopping influence in case, of any failure of ;circuits orthe like;- and it is proposed to utilize the magnetic properties'of an inert body of iron onthe the trackwa for ro- 'ducm the stopping influence. 80' desira le to avoid the use of batteries or "other source of current on the trackway to put the track device into the inactive or non-stopping condition, it is further pro posed. to employ a track element structure 85 which is caused to assume. its inactive condition by merely closing a circuit-without r uirin any electrical energy.

he type of system generally out-- linedabdve, it will be evident that the track 40 rails .oi'crossings, switch points, water pans,

v and similar'iron and magnetic bodies along .the=.trackway, .will tendto produce an effect upon the car equipment similar to that produced. by the regular track elements of the :15 stem when in their active stopping condit on. Such tendency to produce an unnecessary andfalsesto ping control, conveniently termed rail interf erence, is of course, highly objectionable in systems of this character;

' and while variousschemes for overcomin this rail interference have been suggeste it is proposed in accordance with the present tion of ince it is I this application filed May invention to select the location and disposithe cooperating elements on the car and on the trackway in such a way as to practically. eliminate such rail interference. While the general scheme of operation characterizingthis invention may be adapted and extended for the communication of different kinds of influences, for simplicity there is disclosed in this case an arrangement adapted to communicate onl ping influence. 'Also, while suc stopping influence may be employed to initiate or otherwise governthe operation of any suitable form of brake "control or cab signal apparatus, for the purpose of explaining the nature and mode of operation of this invention, consideration is limited to two types or forms of "train control systems, namely, a permissive or semi-automatic sys term in which a brake application is initiated one stop-' at each distant'or caution signal unless the engineer takes ap ropriate action to prevent or hold oif such rake application, and an automatic stop system employing an overlap, in which an absolute and unpreventable brake asplication is produced at each of.

the two a train. I

The variousspecific objects, characteristic features, and advantages of the invention will be in art apparent and in part pointed out as the description of the specific embodiments pro esse's.

In describing the invention in detail, reference will be made to the accompanying drawings, in which Figure '1 is-a simplified and diagrammatic view showing in accordance with established convention one typical arrangement of trackway circuits ada ted to control the track elements of this invention to rovide an automatic stop system with over ap;

2 illustrates the carjequipment designed and' adapted to be used to connection with the automatic stop trackway system shown .in Fig.1; and

Fig. 3 is acontinuation of Fig. 1 and shows the trackway circuits and devices for providing an absolute stop at an interlocked signal.

anger or stop signals in the rear of his is a division of application Sen No.

automatic sto system with overlap and with the rovision of an absolute stop at interloclre signals.

Traclcway apparatus (automatic block term'ziory).

While various arrangements or key-by devices and circuits, acting upon either the track apparatus or the car apparatus, may be employed, there is disclosed in accordance with this invention an arrangement in which a train is allowed to pass a stop signal without a brake application at some selected minimum speed. In other words, after a train has slowed down, or stopped in obedi- I ence to a danger or stop signal, in conformity with the rules, it may pull by that stop signal at 'a slow speed without receiving a stopping iuence. v

The system of automatic stop with overlap is well adapted for use on subways, elevated lines, interurban lines, and the like. The

trains on such railroads commonly include a number cit motor cars, each equipped with train control devices and the same control equipment, so that any motor car may be used at the head end oil the train. In the interests or safety, it is desirable that the train control equipment on each of the motor cars of such multi-car trains should be efi'ec tive to govern the train as a whole, otherwise an adequate car out-out device must be provided for the rear cars, and such device may be improperly or carelessly manipulated to cut out of service all of the motor cars on a train and leave it without any protection. it this is done, then, on account oithe fact that each one out the several motor cars in a train is capable of active cooperation with a track element in its stopping condition, it becomes nec ssary to provide some sort of a socalled retaining circuitywhich allows a n'iulti-car train ct kind to pass a track .ent without stopping itself.

i racibway v;i5"L/3?:Ij3-ll9 simpl arrangement oi? tracirway circuits adapted to con with the above requirements employimp; neuti' ionic distant relays, is s h" "tin. cal illustration oi? ste n ferring to Fig. l, o. f. by insulated the manner" in reoauae track circuitis employed, leaving the other rail free for the return of propulsion current-in electrically propelled railroads; but it should be understood that the regular tworail track circuit for steam roads may be used, or a two-rail track circuit with impedance bonds for electrically propelled roads, all in accordance with well recognized practice. For simplicity, a direct current block signal system has been shown, but by the use of a transmission line,'transformcrs, alternating current relays and other expedients well-known in the art, the same scheme of connections of track elements may be employed in conjunction with an alter-- hating current block signal system. The individual rails are bonded together by bonds in the usual manner, the blocks V and W and the adjacent ends of two other blocks U and X being shown. The parts and circuits associated with the various blocks are the same, at least in ordinary block signal territory, and for convenience have been given like reference characters with distinctive exponents.

Each of the blocks is provided with a track relay 4: at one end and a source of energy, which has been illustrated as a battery 3, at the other end. This system preferably iforms an adjunct to some form of block signal system, and in the particular embodinient it has been shown in connection with color-light signals.

\1 Besides the track relay 4, each block is provided with a home relay H and a distant relay D. These relays are of the usual type, the relay l-l having one of its contacts particularly designed and adjusted to function slightly different "from the other, or standard contacts. ln order to assure that a back contact of the track relay l will make before the front contact of the relay H breaks, this relay being controlled by a front contact of the track relay, the front contact 188 of the track relay 4: has been designed to function as a long-wipe contact. This contact 188 has been illustrated conventionally by a stationary contact shown by an arrow, and a movable contact comprising a resilient finger. Tt is apparent that when such trac relay is energized and then deenergized the contact 188 will not break its circuit until after a short lapse oi time after the usual or standard back contacts of the track relay have closed, it is, therefore, apparent that by proper design or this long'wipe contact,

lllli llfi its operation compared vritlrtlie operation bit the usual. contacts will be such that a standard back Contact will make about the same time er even earlier than. such long" wipe front contact breaks. Tht urpose is to make the front conta t If the home relay open than t baclr contact ldl) of the tra if it is desired, the front {if the track, or an equivalent connection to a local battery. It should be understood that these connections BW and CW'may lead to the same or diflerent batteries of appropriate voltage, all as well-known in the art.

The circuit for energizing the home relay ll of block. V ma be traced as follows commencing at C relay H, wire 191, front contact 188 of track relay 4: wire 192, front contact 1'93 of track relay 4 of block WV.

The circuit for energizing the distant relay D of block V may be traced as follows :commencing at CW, relay D, Wire 19 1, front contact 195 of home relay H. wire 196, front contact 197 of home relay H of block W.

At the entrance of each block is located a pair of track elements T, each of which in the particular form illustrated comprises a shaped core oryoke of magnetic material and a coil 16 surrounding the back portion of said core, as shown. The, U- shaped core is preferably laminated to re duce the flow of eddy currents upon rapid changes of flux through thecore, and terminates in upstanding poles having enlarged pole pieces. 'ln practice these track elements are housed in non-magnetic housings, having sloping or ramped approaches (not shown) so as to protect them from the weather and from dragging equipment of passing trains. These track elements T are 'preferably located outside the running rails and extend a considerable distance above the track railsjso that they have an influence transmitting advantage over crossing railsand certain other magnetic bodies along the trackway. Although these track elements T may be located directly opposite each other on opposite sides of the track, they have been shown arranged diagonally with respect to the trackway. This diagonal arrangemcnt of the track elements follows from a similar arrangement of the car elements on the railway vehicle. In this systcm it is desirable to have the car elements mounted on the trucks of a motor car. and also to have the car elements mounted symmetrically with respect to the first axle of a car regardless of which end of the car is leading. Consequently, one of the car elcments is fastened to the right-hand side of the front truck.- when facing .in one direction: and the other car element is located on the right of the forward truck. when the car is headed in the other direction. thus making a symmetrical arrangement of the car element with respect to either end axle with respect to the front axle of either end I of the vehicle will be given in the description of the operation.

, The coils 16 of these track elements T are connected in series in a manner dependent upon the carapparatus which is to cooperate therewith, but are in each event connected so that the E. M. F.s generated when a pair of cooperating car elements passes thereby will be cumulative. The circuit including the coils 16 of the two track elements T in series may be traced as follows :coil 16 of the track element 1, wire 198, coil 16 of the other track element T, wires 199 and 200, front contact 198 of home relay H, and wires 201 and 202 back to coil 16; and in multiple with the front contact 189 of the home relay H is another partial circu-itcomprising the Wire 2023, back contact 190 of track relay 4,, and wire 204. Thus the coils 16 of the track elements T will be included in a circuit of preferably low resistan'ce, either when the home relay H is energized. I

A three-aspectlightsignal has been illustrated conventionally .by red, yellow, and green lamps, 1', y and g, respectively. This light signal is controlled by the home and distant relays H and D by the circuits shown by dot and dash lines. Since the condition of the light signal is readily apparent when the position'of the relays H and D is known. no further description thereof is considered necessary.

Operation of track'wag apparatus silo um in Fig. 1.-The track devices in Fig. 1 are illustrated in their normal or clear traflic condition, and under this condition the relays H and D will be energized, thus completing the circuit through the lamp {1 indicating a clear tradiocondition and maintaining the coils 16 of the track element T in a closed circuit of low resistance through the front contact 189 of the relay H, thus putting the track elements in their normal, clear or non-stopping condition.

Under these normal conditions, let us assume that a train is in the block U, traveling in the direction of traflic indicated by the arrow and enters the block V. The i of the train in the block V will shunt the track relay 4, thus causing it to drop its armature, thereby'c'losing the back contact 190 and opening the front contact 188. Since the contact 188 is of the long-wipe type, the circuit will be made by the contact 190 before the contact 189 is opened, thus insuring the making of the circuit through the coils 16 of the track elements through the contact 190 before this circuit is broken by the front contact 189 controlled by the rela H which has just been .deenergized by the presence opening of the front contact 188 of the relay 4:. The object in making the front contact 188 retarded is to insure the making of the back contact 190 before the front contact 189 breaks the circuit through .the coils .16 of the track elements, and is for the purpose of providing retaining means, the object of which has hereinbefore been explained, that'is, the first car entering a clear block will not put the track elements T in their stopping condition, which might cause the train to be stopped by the car-carried apparatus of the following cars of such multi-car trains as'have been referred to in this particular system.

The distant relay D is deenergized when home rela H drops, because its energizing circuit is roken at front contact 195. The de-energization of relays D and H will, of course, change the aspect of the light signal to indicate :red, but since this is an obdeemed necessary.

' rupted at the contact 193 of the track re-v vious result which may readily be determined by tracing the dot and dash lines in the drawings, no tracing of these particular circuits for controlling the light signal is With' the block V occupied, no train is apt to be in block-U, at least not one that is moving at a high rate of speed, because it would have had to pass a danger signal .at the entrance of block U, which block was also protected by track elements in their danger condition at that time as will become evident as the description of the operation progresses. If, however, a train would move from the block U into the block while the block V is occupied, no stopping influence will be transmitted to the car apparatus, because the track elements at the entrance of the block V have their coils in a closed circuit, that is. in their clear condition. This feature of this system is, however, harmless since this is a one block overlap system, and the engineer must pass acaution signal and two successive danger signals, adjacent one of which the track devices are in their danger condition, before the occupied block is. reached.

Assume now that the train has left. the block V and has entered the block W. The devices at the entrance of the block W will now assume the sanie condition as the correspondin devices at the entrance of the block when said train entered the block V. Since the train has passed entirel out of the block V, the track relay 4 wil become energized, thus closing its contact 188 and opening its contact 190. The'closing of the contact 188 will not energize the relay H, because its energizing circuit is interlay i of block W, therefore leaving the contact 189 open, and consequently the opening of the contact 190 will put the track ele ments into their danger. condition. The (1118- tant relay D will not be afi'ected b the passage of the train from the block into the block W, and since neither of the relays H and D is energized, the three-aspect colorlight signal at the entrance of block will not be changed by the -movement of the train from the block V into the block W, and will therefore still indicate red or danger.

Assume now that the train which is considered to be occupyinggblock W has moved entirely into the block Under these conditions the home relay H at the entrance of the block V will be, energized, because its energizing circuit will be completed at the front contact 193 of the track relay 4 at the entrance of the block W, because this relay will be picked up at the time the train leaves the block W. The energization bf the home relay- H will cause the contact 189 to be closed, thus putting the track elements at the entrance of the block V in their clear traffic condition. The energization of the home relay H will close the contact 195 in the energizing circuit of the distant relay D. This relay D will, however, not be energized, because its energizing circuit is open at the contact 197 of the home relay H at the entrance of the block W, this home relay H being deenergized because its energizing circuit is open at the front contact 193 of the track relay this track relay in turn being dcenergized on account of the presence of the train in block X. a It should be noted that the presence of a train in the block X with the blocks D, V and W unoccupiedcauses the light si nals at the entrance of the blocks W and X to indicate danger, at the entrance of the block V to indicate caution and at the entrance of the block U to indicate clear.

Assume now, with-the train in the block X, that another train is approaching the block U in the direction of the arrow. Since the signal at the entrance to block U is at clear, the train will continue its normal speed until it approaches the entrance of the block V. As the train approaches the entrance of the block V, the engineer will observe a caution signal indicating that he may proceed into the block V prepared to stop at the end ofthe block. The track elements T, T at the entrance of the block V are in their clear traflic condition. The train, having passed a caution signal now, may proceed under caution in the block V, but if it enters the block W, which has its signal at danger and its track elements in their danger condition, the train will be stopped when passing said track elements by suitable apparatus on the vehicle to be described hereinafter.

Speed-'c0ntr0Z.-If the engineer, however,

has observed thecaution signal and has reduced the speed of the train to a predetermined extent, say to five miles per hour,

Inc

he may pass into the block W without receiving such a danger or stopping influence. This is due to the fact that the first axle of the train will bridge the rails of the block W, thus deenergizing the track relay 4 causing the back contact 190. of the track relay 4 to be closed a short time after I such deenergization. In a relay of the usual construction, the time necessary for its contacts to complete their movement is in the neighborhood of four-tenths of a-second; and consequently the track elements at the entrance of the block W will be put in their clear or short-circuited condition about not higher than five miles per hour, will allow sufficient time to elapse for the contact 190 of the track relay 4 'to close, thereby putting the track elements in their clear con dition before the car elements pass thereby. If, however, thetrain enters the block at a higher speed than five miles per hour, in-

sufiicient time will have elapsed to allow the contact 190 to close, consequently bringing the car elements by the track elements before they are in their clear condition, thus transmitting a stopping influence to the car apparatus. Although practical results have been obtained by the use of relays of the usual construction, and not provided with any retarding devices, such retarded or slow acting relays may be used instead.

Structure of car apparatus in F ig. 2.-Qne particular arrangement of car apparatus and circuitsfor causing an absolute and. unpreventable brakeapplication after an influence has been transmitted thereto, and particularly adapted to the one block overlap trac'kway system just described, has been illustrated in Fig. 2. In this system of car apparatus, two car elements L and L arrangeddiagonally onopposite sides of the car are provi ed. These elements L-L comprise U-sh ped cores terminating in enlarged pole'pieces having a primary coil P on one leg thereof and a secondary coil S on the other leg These secondary coils S and S are connected in series so thattheir effect is cumulative; 1

The car-elements L-L are dis osed diagonally opposite each other for t e purpose ofarranglng them symmetrically with respect to either end "axle-of the car, for the reasons previously explained. This system employs three re a trol relay C which is provided with light ys, namely, a maini-conmoving parts, thus operating on little ener I changes, a repeater relay R which is actuated by the main relay but is of a heavier construction, therebypermitting the control of larger currents thereby; and a check relay (JR arranged in series with the primary coils P-P of the carelements, so that if the circuit through these primary coils is entirely interrupted, or if the current depreciates to an extent below a value necessary to make -thesecar elements function, this check relay Will drop its armature 205 and through intervening mechanism apply the brakes. These relays are designed for the particular purpose for which they' are to be used and are preferably provided with balanced moving parts, so that they will not be apt to be actuated by jars, vibrations, and the like.

The brake control device comprises an electro-pneumatic valve E. P. V. which is constructed to vent the train pipe directly when its winding 206 is deenergized, and is provided with two pairs of make-beforebreak spring contacts 207 and 208 which are %ened and closed respectively when this P. V. is deenergized. The valve construction of this E. P. V. may be such as to effect a service brake application, or an emergency brake application, as desired, this being dependent upon the size of the the valve opening when the E. P. V. is deenergized.

Another part of this particular car-carried" apparatus comprises a pneumatically operated switch, for convenience called an air-switch. This air-switch AS consists of a cylinder 209 of suitable size, having its closed end connected to the brake pipe BP. This cylinder 209 is provided with a piston 210 making an upper air-tight chamber, and having a piston rod 211 extending therefrom through the other end of the cylinder.

bear against the under side of the-piston 210, air vents 2l2 have been provided. The other end of this piston rod 211 has an insulated' movable contact 213, adapted to contact with the stationary contacts illustrated as arrows when the iston 210 is raised. The raising of 210 is ue to the spring 214 on the piston rod 211 between the piston 210 and one end of the cylinder. Under normal conditions, that is, with running brake pipe pressure in the cylinder 209, the spring 214 will be compressed, thus moving the movable contact 213 away from the stationary contacts. If new the pressure inthe brake pipe'BP is reduced to a predetermined extent, this spring 214 will move the-piston 210 against the pressure in the brake pipe, thereby bringing the 'movable contact 213 against the stationary contacts. The spring 214 is referably of such strength that the air-switcli will not close until after a lapse of time following the necessary vent- In order to permit atmospheric pressure to ing of the brake'pipe, which is long enough to assure that the train has come to a stop from its maximum attainable speed. In practice, this desired time control is ob- ES tained by venting the brake pipe pressure to such a low value that the required time consumed in venting the brake pipe below that necessary to effect a full service brake application, so that the train is stopped before contact 213 closes.

This particular car apparatus -is provided with two batteries, namely, a main battery 215 and a small secondary or relay battery 216. The main battery 215 is sumed to be the source of energy commonly used in a multi-cur system for the purpose of operating the multiple-unit control system, doors, bells, and a reserve source of energy for illumination. Such a battery is usually floated across the third rail in the case of electrically propelled vehicles, and its voltage varies considerably. The small battery 216 is provided to give a more constant potential source of supply for the pur pose of energizing the main control relay C and the repeater relay R. In this system a reset bus 217 has been provided, whereby the control apparatus on any one of a plurality of connected motor cars may be reset from any one of the cars; and although in the particular system herein described, it is seldom necessary to resetmore than the apparatus on the first car, it is nevertheless desirable to be able to reset the apparatus on any car in the particular train from the motormans cab in use at that time. A reset push button 218 is located in each motormans cab at a convenient place. She operation of this reset button 218 and bus 217 will be explained in, the operation of the car apparatus.

The energizing circuit for the main control relay C may be traced as follows :-beginning at the positive side of the small or relay battery 216, wire 219, front contact 265 of check relay CR, wire 220, armature 221, and front contact 222 of main relay C, wires 223 and 224, secondary coil S, wire 225, secondary coil S, wire 226, winding of main relay C, wires 22? to 230, winding of check relay CR, wires 231 and 232, and back to the negative side of the small battery.

The circuit for energizing the repeater relay R may be traced as follows :-starting at the positive side of" the small battery 216, wire 219, front contact 205 of check relay CR, wire 220, armature 221 and front contact 233 of main relay C, wire 234, winding 0t repeater relay R, wires 235, 229 and 230, winding of the check relay CR, wires 231 p and 232, and back to the negative side of the small battery.

The energizing circuit of the primary coils P and P may be traced as follows :beginning at the positive side of the large neonates battery 215, wires 236 and 237, primary coil P, wire 238, primary coil 1?, wires 239 and 231, winding of check relay CR, wires 230, 229, 228, 240 and 2 11, and back to the negative side of the large battery.

T he energizing circuit for the winding 206 of the E. P. V. may be traced as fol lows z--starting at the positive side of the main battery 215, wires 236, 242 and 243, front contact 207 of the E. P. V., wires 2% and 2&5, front contact 246 of the repeater relay wire 24:7, winding 206 of the E. P. V., wires 2%, 229, 228, 24-0 and 2&1 and back to the negative side of' the battery.

it is thus seen that the energizing current of the primary coils P and P flows through the winding of the check relay GR in one direction, and that the current for energizing the main itrol relay C and the repeater relay R flows through the winding of the check relay CR in the other direction. Since the current in the primary circuit is much larger than the current for supplying the relays C and B, it is obvious that a voltage drop due to this primary current will result across the winding of the relay CR, and tl'aat this voltage drop will be in a direction to increase the voltage across the relays (I and R. Thus, when a voltage of the main battery 215 increases, due to an increase of voltage on the trolley or third rail across which this battery floats, the current flowing in the primary circuit will he likewise increased, and this increase in current will cause a slight increase in voltage across the relays C and R, thereby compensating to a certain extent the voltage across the relays 'J and B when a voltage change takes place across the primary coils in the primary circuit. Such a compensation is desirable because the induced voltage in the secondary coils S and S which opposes the voltage of the small battery 216, as will appear hereinafter, is dependent upon the strength of the magnetic fields produced by the primary coils P and P and therefore it is desirable to change the potential across the relay in a definite relation to a change of magneto-motiveforce produced by the primary coils of the car elements.

Operation of car apparatus in F i 2- Assume now that a car e nipped with the apparatus illustrated in ig. 2 is moving between control points with this apparatus in its normal condition as illustrated, that is, with the relays C, R and CR, the winding of the E. P. V., and the rimary coils P and P energized through to circuits heretofore traced; and that this car apparatus passes over a pair of track elements IT in their danger condition, that is, withftheir windings 16 open circuited. This coo ration of the car-carried elements an the track elements T causes the flux passing through the secondary coils .S and S to greatly increase. This increase of the flux through the secondary coils is believed to be due to both an increase in the total flux through the primary coils and a diversion of flux from leakage paths. As the car element recedes from the track element, a cor- :responding decrease of flux through the sec.-

current, thesesecondary coils being so conondary coils takes place. The rapid momentary increase and decrease of the flux through the cores of the car elements induces a voltage in the secondary coils S and S similar to a. single cycle of alternating nected thatthese induced voltages are cumulative, and are so connected n the circuit I with the small battery 2.16 that the first wave tion'to the voltage producedby the small" I voltage of the single cycle of E. M. F. is in opposibattery'and the resistance drop acrossthe check .relay CR.- This first wave of the generated in the secondary coils S and decreases the current in the main control relay C to a suiiioient extent to cause picke venting oflthe v brake it.to drop its armature 221 and open both of its frontcontacts, thus entirely interrupting its energizing circuit and also the energizing circuit of the repeater 'relay B, thesey circuits having been heretofore traced.

The deenergization of the repeater relay R causes its front contact 246 to open and interrupt" the energizing circuit of the E. P. V., which, when deenergized, will vent the brake pipe BP and apply the brakes to bring the train to a stop. During such ipe BP the brake pipe pressure will gra ually decrease, and when it has decreased-tothe predetermined extent for which the spring 214 in the air-switch AS has been designed said-switch will be closed, thus shuntingthe front contact'222 of the main relay C, thereby picking up this relay which will stay energized throu h said front contact as soon as it is i d up (this being a stick relay). As soon as the main relay C is energized its other" front contact 233 will complete the energizing circuit for the repeater relay R, thus causi'n 246. The c osing of this front contact 246 of the repeater relay R will, however, not

energizet' he E. P. V., because this E. P. V.

is likewise of the stick type, its energizing v circuitbeing interrupted at its own front 'contacts 207.,

. wire 25 1, 'backcontaot'208 of the E. P. V

To energize the E. P. V., the resetbutton 218 in any one ofthe motormanscabs of a .rnulti-unit train is closed. This closes a pick-up circuit that may be traced as follows :--b.eginning at the positive side of the large battery 215 located on the car in question, wires 236, 242, and 249, reset button'21'8 located on the Carin-question, wire 4 250, reset bus 217,;through the following apparatus on any one of the cars in the train,

it to close its front contact' and a sufiicient brakewires 252 and 245,-front contact 246 of the repeater relay R, wire 247, winding 206 of -on the particular car Whose reset button has been operated, thence wires 253 and 241 back to battery 215.

It should be noted that the contacts 207 and 208 operated by theE. P. V. are of the spring type, and are so designed that the top or front contacts 207 make as the E. P. V. is energized before the back or bot tom contacts 208 break. This is done in orderto ,permit the stick circuit oftlie E. P. V. to be closed before the pick-up circuit thereof is interrupted by the back contacts 208 of the E. P. V.

If the coils 16 of the track elements T are in-a'closed circuit of low res stance, no effeet is produced on the car apparatus because there is insuflicient change of flux through the secondary coils to cause operation of the control relay C. This is attributed to the fact that the coil 16 on the core of each track element T, being in a closed circuit of low resistance acts as a choke coil to oppose or choke back the passage of flux through said core. Putting it another way, as soon as the primary coil 1 tries to send flux through the core 15 of the track element T, this changing flux induces in the coil 16 a voltage that, in accordance with well known princlples, tends to send a current in a direction to create a field opposing the flux inducing such voltage. In any event, it is found that by selecting the proper number of turns for the coil 16 of the track element, with regard to the strength of the primary field, sensitiveness of the relay C, and other factors, an organization may be obtained in which the inclusion of the coil 16 in a circuit of relatively low resistance permits passage of the car element without operation of the control relay C, whereas, with this coil open circuited, said relay will be operated.

Some of the features of advantage of this system are that the voltage across the main control relay C is automatically compen-' sated' asthe energizing current through the primary coils PP of the car elements changes, the check relay CR serving both to check the integrity of the primary c-ircuit and assure the'flow of sufiicient current therein to make the car elements function properly, and also as a compensating resistance for automatically .compensatlng for fiuctuationin the main battery voltage, as explained. The system can only be reset, after an automatic brake application has been made, after asuflicient time has elapsed pipe'pressure reduction'has been made. Absolute stop at interlocked signals.'A

particular system of car apparatus for causmg an absolute and unpreventable stop when a stopping influence has been transmitted thereto has just been described in connection with a trackway system, comprising an overlap and having means whereby a control influence will not be transmitted to the car apparatus unless the vehicle passes a stop signal above a predetermined speed, taken, for example, at five miles or hour. A system of this kind is satisactory for ordinary block signal territory, but

is not desirable where an absolute stop is necessary, such as at the entrance of an interlocking plant or like conflictin route where a train shall not pass a stop signal at any speed, because it may get in the way of a fast moving train using a conflicting route.

For a semi-automatic train control system the desired absolute control at an interlocked signal may be obtained by using regular derail devices, but such devices have some objections and are not applicable to subways or elevated railway systems for reasons apparent to those skilled in the art, and it is therefore desirable to provide an arrangement by which the train will be stopped by an unpreventable brake-application if it attempts to pass an interlocked signal in its stopping or danger position. This may be accomplished by locating one or more inert track elements directly opposite the signal, so that while the train may pull up to the signal, the E. P. V. would be operated and the brakes automaticall applied it the train attempts to pass suc signal at stop. As previously explained, communication of stopping influences are dependent upon change oi' llux, requiring certain relative motion between the car and track element; and although this action may take place at a very low speed depending upon the design of this apparatus, ii desired, an absolute stop element acting at the lowest possible speed may be employed in addition to, or as a substitute for, the regular inert element at the interlocked signal.

For the purpose of explaining the nature and mode oil operation of an arrangement embodying this invention for enforcing absolute brake application at interlocked signal at the lowest possible speed, there are shown in log. 3 in a simplified and diagrammatic manner two intersecting stretches oi track, together with track devices and circuits, which have been selected as a typical illustration oi the control for the conflicting routes found in interlocked territory. o .e traclt, comprising" blocks Y and Z, for coir venience called the main track, may be con sidered to be a continuation of the stretch oi tracleshown in Fig. l. is contemthat the same arrangement and con fecli; elements and signals, that woman been shown in Fig. 1 and hereinbefore described, will be used on the two stretches of track shown in Fig. 3; but to avoid complication, the description of some of the circuits for carrying out said scheme of automatic stop with overlap has been omitted.

The signals, track elements and control circuits associated With the two intersecting stretches of track in Fig. 3 are the same; and for convenience the relays and other devices thereof are given the same reference characters as in Fig. 1, with exponents land 5 added. The additional devices used to obtain the absolute stop control. being the same for the block. Z, and. the block Z-Z, will be given the same reference characters with the distinguishing exponent a.

At adistance from the point of intersection of the conflicting routes, shown as the entrance to the blocks Z and ZZ, are home signals, which are the color light signals, the same as used in block signal territory, and which govern traffic over the respective routes in the direction indicated by the arrows. These home signals are controlled in conformity with established interlocking practice, both by track circuits and also by levers and associated equipment at a central point or tower 25%. The levers for the home signals in question have been shown for the sake of simplicity in the form of push buttons 255 255. These levers are mechanically interlocked in the usual way, and are provided with electric locks, indication mechanism, and other devices common in modern interlocking practice.

At each home signal is located a pair of track elements T, the same as used in block signal territory (Fig. 1), and a pair of additional or auxiliary track elements TS designed to assure the transmission of a stopping impulse at the lowest possible speed oi? the train. The auxiliary track elements T constitute similar magnetic cores and coils and these coils are at times energized by alternating current of a commercial frequency, shown in this instance as derived from transformers 256256", the primaries of which are connected to a suitable source of alternatin current (not shown). For the purpose of checking the inte r rit of the energizing circuit for the auxiliary track elements TS, so as to be sure of control of train. movement on the side of safety in the event of a circuit failure, there are provided checlz; relays 25! 257, of the usual. alter hating current type, which may be located in the tower shown, or at some other fipcmtion of Fig. 3. The mode of opera- 1 tion for train. movements over either of the intersecting stretches oi? track shown i is the same, and a description of a ment over main st tltl ilti

llltl llll indicates danger or stop, and the corresponding track elements '1 and TS are in the active stopping condition. In the case of the regular track elements T thisstopping con dition is due to the fact that their coils 16 are open circuited at the front contact 189 of the home relay H, since the lever 255, is in its normal position and the energizing circuit for said home relay is broken at thei normally opened cont-acts 258 of said lever. This energizing circuit of the home relay H may be traced as follows :-commencing at the common wire CW, relay H, wire 191 front contact 188 of track relay 4:", wire 192*, front contact 259 of check relay 257, wire 260, contacts 258 of lever 255, wire 261, and thence through a frontcontact ofthe track relay of the block next in advance of the block Z (not shown).

The auxiliary track elements TS of the block Z are normally energized by alternating current, due to the existence of a circuit which may be traced as follows :commencing at one terminal of the coil of the upper or lefthand track element TS, wires 262 and 263, secondary of transformer 256, wire 264, check'relay 257, wire 265,- contacts 266 of lever 255, wire 267, back contact 268, of home relay H wires 269 and 270, coil of track element TS, and wire 271 to the coil ofthe first mentioned track element TS.

It will be noted that this energizing circuit includes the checkrelay 257 which, as shown by analogy to the energizing circuit for the home relay H above traced, governs theenerg-izing circuit for the home relay H of the conflicting route, so that the home relay of said conflicting route can not be energized to clear the signal and allow the pas} sage of a train unless the track elements TS are actually energized by alternating current, the existence of such energization bein indicated by; the fact that the check relay 25 is icked up. Likewise, the track elements T are normally energized by alternating current and pick up the check relay 257*, which governs the energizing circuit for the home relay 3.

Under the normal conditions above described, the regular track elements T, being open circu ted, will effectively-stop a train attempting to enter the block Z at a speed sufficiently high to induce enough voltage in the secondary coils of the car elements to actuate the brake control apparatus. The exact speed at which this stopping action will occur dependsof' course upon the size and proportion of the parts, lengthof the air gap. and the like; and wh le by; appropriate design, such stopping action maybe caused to take place any speed above a very low speed, such as three or four miles per hour, the -auxiliary track devices TS, being energized by alternating current, will act to cause a stopping influence at the slowest possible speed, and even when the car element stands stationary over these track elements. It will be readily appreciated that such action is due to the fact that the alternating flux produced by the track elements TS Will alternately oppose and assist the flux of the primary coil on the car, and re.-

gardless of relative motion, induces Voltage changes in the secondary coil that will at times oppose the voltage in circuit with the main control relay, thereby causing it to drop and apply the brakes, in the manner hereinbefore explained.

Assume now that the operator in the tower 254 desires to clear the route over the main track comprising blocks Y and Z. He reverses the lever 255, opening contacts 266 and closing contacts 258. The opening of contacts 266 breaks the energizing circuit for supply alternating current to the track elements TS; and the closing of contacts 258 closes a break in the energizing circuit for the home relay H If the track elements TS at the entrance to the block Z-Z thereby clearing the signal of block Z. The

energization of the relay H similarly causes clearing of the signals at the entrance to the blocks X and Y, in the mannerpreviously explained.

When the home relay I-I picks up, its front contact 189 closes and puts thevtrack elements '1 in their clear condition by establishing a closed circuit for the coils 16 of said track elements. Also, the front contact 268 of the relayH closes and establishes a low resistance circuit for the coils of the auxiliar track elements TS, which may be traced as follows :commencing at the u per element TS, wires 262, 272 and 273, f coil of other elements TS, and wire 271. Trains may now pass through the block Z without receiving an automatic brake application. A train entering the block Z will'put to stop the signals and track elements T in the rear in the same way as in block signal territory;-but until the operator shifts the lever 255 back to the normal position, the

track elements TS are not energized, be-

lot

ront contact 268, wires 269 and 270,

" cause under the conditions described, that is, I

only the regular control for block signal territory is required.

Since it is assumed that multi-car trains will be-employed, an arrangement of retaining circuits is provided for the track elements at the entrance to the blocks Z and ZZ to hold these track elements in the clear condition as the first car enters these blocks, in order to avoid premature stopping of some of the rearcars. In the case of the regular track elements T, this retaining is accomplished in the same way as previously explained, that is, by providing a shunt for the coils of the track elements T controlled by the back contact 190* of the track relay 4*. 'In the case ofthe auxiliary track elements TS, there is provided a similar shunt for their coils controlled by an additional back contact 274 of the track relay and comprising wires 275 and 276.

The low speed key-by feature hereinbefore explained in connection with automatic block signal territory in Fig. '1 is not, however, used in connection with the track elements T and TS at the entranceito the blocks Z and ZZ; and both pairs of these track elements are so located with respect to the insulated joints that they will be encountered by the car elements of a passing vehicle before the first axle of that vehicle Eassesover said joints, or at least before the ack contact of the track relay closes. Such specific location is, of course, selected with due regard to the customary practice of allowing a train to pull completely up to the signal; and if necessary, the signal may be located a short distance in the rear of the insulated joints.

One of the important features of the absolute stop arrangement shown in Fig. 3

' consists in'the provisions made for checking the supply of alternating current to the auxiliary track elements TS. It is contem- Slated that this alternating current will be erived from a reliable source, with one or more independent sources in reserve, so that aside from local circuit or contact failure, each pair of auxiliarytrack elements TS throughout [the interlocking plant will always be energized with alternating current, when desired to block train movement. The application of alternating current to each individual pair of these track elements TS is automatically checked by a check relay 257; and unless this check relay is energized, the signals and train control track elements of any conflicting routes can not be cleared. In the event of a current failare after a route has been set up, a contingency that is far remote, the check relay 1257 will automatically detect such failure and at once put to stop the signals and track devicesof'any conflicting route that may be clear, thereby at once stopping train movement on this conflicting route.

While there have been shown and described various specific constructions and arrangements of parts and circuits for practicing the invention, and the mode of operation and many of the advantageous features of these constructions have been pointed out, it should be understood that this disclosure does not exhaust all of the various embodiments of the invention, nor include the 'various auxiliary devices and methods of signal and train operation well known in the art and commonly practiced. The specificdisclosure herein is, therefore, susceptible of considerable adaptation and modification in practice, without departing from the invention.

What I claim is 1. A train control system of the type in which control influences are transmitted from the trackway to the vehicle through an intervening air gap comprising, an impulse receiving stick relay, a train control device connected in a stick circuit governable by said relay, automatic means effective only after the train has been brought to a stop for resetting said stick relay, and manual means for resetting said train control device.

2. A train control system of the type in which control influences are transmitted from the trackway to the vehicle through an intervening air gap comprising, an impulse receiving stick relay, a train control device connected in a stick circuit governable by said relay, pressure responsive means for resetting said stick relay, and manually operable means for resetting said train control device.

3. A train control system of the type in which control influences are transmitted from the trackway-to the vehicle through an intervening air gap comprising, an impulse receiving stick relay, a train control device connected in a stick circuit governable by said stick relay, and manually operable means for resetting said train control device, said manually operable means only being effectual when said train control device is in its operative position.

4. A train control system ofthe type in which control influences are transmitted from the trackway to the vehicle through an intervening air gap comprising, a carcarried element consisting of a core having a primary winding, a source of current for energizing said winding, a secondary windlllti ing on said core connected in'series with an electro-responsive device for controlling the brakes of the vehicle, and another source of energy including means for varying its voltage in a definite relation to the variation of the voltage of the" first mentioned source.

5. A train control system of the'type in which control influences are transmitted from the trackway to the vehicle through an intervening air gap including,an electrically operated brake control device normally energized through front contacts controlled by said device, and means forreenergizing said device when deenergized through a cirwith said core for transmitting controlling influences to said car-carried element comdead magnetic core when in its influence transmitting condition, and another track element consisting of a core of 'magnetic material having a coil thereon energized by alternating current when in its influence transmitting condition.

7. A train control system of the type in which control influences are transmitted from" the trackway to the vehicle electromagnetically comprising, a car-carried element consisting of a magnetic core having an influence receiving winding thereon, a stick relay having its stick circuit connected to said winding, brake control apparatus controlled by said relay, a trackway element consisting of a core having legs extending above the top of the track rails and having a winding thereon energized by alternating current when in its influence transmitting condition for efi'ecting the winding of said car-carried element to drop said stick relay when said car-carried and trackwayzelements cooperate, and ressure responsive means for resetting said stick relay. 8. In a train control system of the type in which control influences are transmitted .electro-magneticall through an intervening air gap, car-carrier apparatus including influence receiving means, and brake control apparatus governed thereby; and trackway means comprising track elements for transmitting control influences to said influence receiving means, said track elements being operated by suitable track circuits in a mannor to put them in their danger condition when the block which they-protectis unoccupied-and the next block in advance is occupied, and to put them in their clear trafiic condition when both of said blocks are occupied.

9. In a train control system of the type in which control influences are transmitted,

electro-magneticallg through an intervening air gap, car-carrie apparatus including intrain in said block, P151110 one track element consistln of a on,'means for magnetizing said core, elecfluence receiving means, and brake control apparatus governed thereby; and trackway means comprising track elements for transmitting control influences tosaid influence receiving means, said track elements being operated by suitabletrack circuits in a manner to put them in their danger condition when the block in whichthey project is unoccupied and thenextblock in advance is occupied, and to,put themin their cleartraflic condition when bothjof said blocks are occupied, said track elements being placed a distance in advance of the beginning of the track circuit so that a train entering a block when the next block in ad- Vance is occupied at a predetermined low maximum speed, will not encounter the track elements until they have assumed their clear conditiondue to the entrance of said 10. In a train control system adapted for block signaledand interlocked territory, the combination of a car-carried means including a magnetic 'core having a windinglthere- 9o tro-responsive means for controlling the train governed by said winding; and a trackway means for block signaled territory effective in transmitting control influences when a train is traveling at speeds above a predetermined low maximum speed, and another tra'ckway means for interlocked territory efl'ective in transmitting control influences at very low speed or when said car-carried means stands directly over' said another 1 trackway means.

11. In an automatic train controlsystem, the combination with means on a railway vehicle inductively responsive to alternating current flowing in a trackway circuit for automatically applying the brakes on :1 vehicle dependent'up'onthe flow of such current, and trackway apparatus for conflicting routes of trackway comprising a circuit for each of said routes and a source of alternating' current therefor, and manually operable interlocked electrical switching means for controlling the flow of alternating current in said circuits.

12. In an automatic train control system, 115,

the combination with means on a railway vehicle inductively responsive to alternating ually operable means for controliing the flow "ofalternatin current in said circuits, and

means contro' led in accordance. with the flow of current in the conflicting trackway circuit for preventing said'manually operable means from being effective.

13. In an automatic train control system, the combination with means on a railway vehicle responsive to alternating current flowing in a tracnway circuit for automatically applying the brakes on a vehicle in accordance- \vith the flow of such current, and trackway apparatus for two conflicting sections of trackway comprising a circuit and a source of alternating current associated with each of said trackway sections, and manually operable means dependent for its efiective operation'on traffic conditions ahead of the section in question for controlling the flow of current in each of said circuits.

14. in an automatic train control system, the combination of car-carried apparatus including a car element havin an exciting coil, an influence receiving coi and an electro-responsive device of the stick type controlled by said receiving coil, and of trackivay apparatusadapted to cooperate with said car element comprising a track element of magnetic material, a coil on said track element, and means for closing said coil in a closed circuit of low resistance under clear trafiic conditions and for energizing said coil by alternating current under danger traffic conditions.

15. In an automatic train control system, the combination of car-carried apparatus including a car element having an exciting coil, an influence receiving coil, anelectroresponsive brake controlling device of the stick type controlled by said receiving coil, and manually operable means for restoring said device to normal only after operation thereof, a trackway element comprising a core, a winding on said core closed in a circuit of low resistance under clear trafiic conditions, and a source of alternating current adapted to deenergize said electro-responsive device by inducing a voltage in said receiving coil when said car element passes over a trackway element in its efi'ective stopping condition.

16. in an automatic train control system, the combination with car-carried apparatus comprising a car-carried core of magnetic material, anormally excited primary winding on said core, an influence receiving Winding on said core, and trackway equipment for etl'ecting automatic control of said car-carried apparatus when the car travels at an excessiy e speed under danger traflic conditions ahead, said trackway equipment including a trackwa element adapted to transmit a control in uence to said influence receiving coil, and control means for putting said trackway element in its active stopping condition under danger tratiic conditions ahead and for putting it in its clear nonstopping. condition a predetermined time after a train passes a point a predetermined distance in the rear of said element.

17. Car-carried apparatus for automatic panacea train control systems comprising, a core cit magnetic material, a primary Winding and a secondary winding on said core, a source of direct current for energizing said primary Winding, another source of direct current for energizing a rela connected in series with said secondary winding, and means for automatically varying the current flow through said relay in accordance with voltage changes of said first mentioned source.

18. In an automatic train control system, the combination with car-carried apparatus comprising a control relay energized by a circuit includingafront contact of said rclay, a brake control device acting on the usual air brake system controlled by said relay, means for shunting the front contact of said control relay only if the brakes are appiled to a predetermined extent, and track- Way equipment including a trackway element adapted to transmit a control influence to momentarily deenergize said control relay when in its active stopping condition, and control means for putting said track- Way element in its active stopping condition under danger traflic conditions ahead and for puttin it in its clear non-stopping condition a pre etermined time after a train passes a point a predetermined distance in the rear of said element.

19. In an automatic train control system, the combination with a railway vehicle, car elements on opposite sides of the vehicle each having a primary and a secondary coil surrounding a core of magnetic material, a circuit including a source of energy, said primary coils and a train control device, a relay, a circuit including said relay and said secondary coils, and trackway elements located along the trackway in position to simultaneously cooperate with said car elements and change the magnetic reluctance of its corresponding core as the vehicle passes by said trackway elements.

20. A train control system comprising, a brake control device on a railway vehicle, a control relay energized by a circuit including a front contact of said relay for controlling said brake control device, apparatus partly on the vehicle and partly along the trackway for momentarily deenergizing said relay under predetermined traihc conditions ahead, and means etlectiveit' the pressure in the brake pipe of the vehicle is reduced to a certain value fol-shunting the contact of said relay.

21. A train control system comprising, a brake control device on a railway vehicle, a control relay energized by a circuit including a front contact of said relay for controlling said train control device, apparatus partly on the vehicle and partly along the trackway for momentarily deenergizing said relay under predetermined traffic conditions ahead, and means including a manually oplid till

till

llilti lid erable device for restoring said brake control device to normal after an automatic actuation' thereof, said last mentioned means being effective onlyif the brake pipe pressure on said core, a source of direct current for energizing said primary winding, another source of direct current for energizing a relay connected in series with said influence receiving coil, and automatic means included in a common portion of said two circuits for. varying the current 1n said relay in accordancewith the variation of current in said primary winding.

24;. An automatic train control system comprising, car- *arried apparatus including a core of magnetic material having a primary and a secondary winding thereon, a direct current source of energy for energizing said primary winding, a brake'control device actuated upon the reception of a control influence by said secondary winding, and trackway equipment magnetically cooperating with said core for transmitting control influences to said secondary winding, said trackway equipment including a track device comprising an inert body of iron when in its active stopping condition, and another track device energized at times by alternating current.

25. In t'ackway apparatus for an auto matic train control system for governing trains over conflicting routes at interlocking plants, the combination with two tracks of conflicting routes, a circuit assoclated with each of said tracks and adapted to transmit control influences inductively through an intervening air gap to suitable train carried train control a paratus, said circuits being interlocked so tlat only one of said circuits may be in the clear trafiic condition at one time,

26. In trackway apparatus for automatically governing train movements over conflicting routes at interlocking plants, the combination with two tracks having conflicting portions, a circuit associated with 'ergizing said primary winding;

each of said tracks and adapted to transmit control influences inductively to suitable train carried train control apparatus, and manually operable means for energizing said circuits, said manually operable means being ineffective to put one of said circuits in its clear traflic condition while the other circuit is in its clear traflic condition or While the conflicting track portion is occupied.

27. In an automatic train control system; the combination of car-carried apparatus including a control relay having a front contact; a secondary influence receiving coil; a secondary circuit including the winding and front contact of said relay, said secondary coil and a source of energy in series; means governed by said relay for bringing the train to a stop when said relay assumes its retracted position; and of trackway means including a trackway device for inducing a voltage in said secondary coil upon passage of said coil by said trackway device when in its active condition; and means for rendering said trackway device inactive a predetermined time after an approaching train passes a point a predetermined distance in the rear oi -said trackway device; whereby the train is only stopped it it travels above a predetermined speed when approaching said trackway device.

28. In an automatic train control system; the combination of a car-carried apparatus including a control relay having a front contact; a car element comprising a core of magnetic material having a primary and a secondary winding thereon; means for ena secondary circuit including the winding and front contact of said relay, said secondary Winding and a source of energy in series; brake control means governed by said relay; and ot' trackway means including a trackway device for inducing a voltage in said secondary winding by flux emitted bysaid primary winding upon passage of said car element by said trackway device when in its active condition; and means for rendering said 'trackway device inactive a predetermined time after an approaching train passes a point a predetermined distance in the rear of said trackway device; whereby the brake control means is operated if the train travels above a redeterniined speed when approaching sai trackway device.

In testimony whereof I aflix my s1gna-"- ture.

CHARLES s. BUSHNELL. 

